On berry ranches, harvested berries are typically first placed in ventilated primary plastic containers. These filled primary plastic containers are then placed in a secondary box or container. The secondary container typically includes a bottom wall, a pair of opposing side walls, and a pair of opposing end walls. After loading a given number of the filled primary containers into the secondary container, the secondary container is loaded onto a pallet. The process of filling primary plastic containers, loading a given number of the primary containers into a secondary container, and loading the secondary container onto the pallet is repeated until the pallet supports a predetermined number (e.g., 96) of secondary containers. The secondary containers are typically arranged on the pallet in multiple stacks. For example, if the pallet supports 96 secondary containers and the dimensions of the pallet are sufficiently large to accommodate six secondary containers per layer, the secondary containers may be arranged in six stacks with 16 secondary containers in each stack.
After the predetermined number of secondary berry containers are loaded onto the pallet, the loaded pallet is moved to a refrigeration unit to cool the berries. Since the refrigeration unit has a limited capacity, it is important that both the primary and secondary berry containers be designed for optimal cooling efficiency. To optimize cooling efficiency, both the primary and secondary berry containers are provided with strategically positioned cooling vents. Cool air from the refrigeration unit is forced through the vents in both the primary and secondary berry containers. The vents in the secondary berry container are designed to generate turbulence within the secondary container, thereby assuring cold air flow through and around all portions of the berry-filled primary containers.
To promote optimal cooling efficiency, which in turn enhances berry quality and shelf life, each end wall of the secondary container may be provided with a large opening. Cool air from the refrigeration unit flows through the secondary berry container via the large openings in the end walls thereof. Since the cooling speed is proportional to the amount of cool air flowing through the secondary berry container, it is desirable to maximize the size of the opening in the end walls of the secondary container. Increasing the size of the openings, however, compromises the structural rigidity of the secondary container. The secondary berry container must provide torsional and flexural rigidity in order to exhibit superior stacking performance. Without structural rigidity, containers at or near the bottom of a stack could buckle under the weight of the containers stacked above them. Due to this buckling, the berries in one or more containers may either be damaged or destroyed. Furthermore, without structural rigidity, the containers could sway or vibrate, thereby causing abrasion damage to the berries.
Accordingly, a need exists for a stackable secondary berry container which provides structural rigidity while optimizing cooling efficiency.